In LTE (Long Term Evolution) scheme, out-of-band emission rules and the like are defined such that interference is not exerted to radio systems used in the same area. In general, the rules are defined by domestic regulations, so that communication carriers are required to operate radio systems based on the rules.
On the other hand, it is assumed that, depending on usage of bands or on the system types, there is a case where sufficient attenuation cannot be obtained for allowed interference level to adjacent systems.
Especially, in LTE, since wideband transmission is performed, noise due to spurious tends to reach far-apart frequency with a high level. Thus, there is a case where satisfying the rules is not realistic by suppression using an analog device such as a duplexer.
For dealing with such a case, in the LTE scheme, a rule is specified such that the transmission power of the user apparatus UE may be reduced according to transmission position and the number of RBs (resource blocks). An allowable maximum reduction amount of transmission power is defined as “A-MPR (Additional-Maximum Power Reduction)” (refer to non-patent document 1).
However, since the radio system that should be protected does not always exist in each country and each area, application of the A-MPR is allowed when a specific signal “NS (Network Signaling) value” (to be referred to as NS value hereinafter) is broadcasted from a network (base station eNB).
The NS value is a value broadcasted by additionalSpectrumEmission of SIB2 (SystemInformationBlockType2) (non-patent document 2). FIG. 1 shows an example of NS values and corresponding transmission conditions (Requirements, band, bandwidth, the number of RBs, allowable A-MPR value) (excerpt from Table 6.2.4-1 of non-patent document 1). More specifically, the “transmission condition” is referred to as “additional spectrum emission mask and Additional spurious emissions requirements” (additional spectrum emission and Additional spurious emissions requirements).
For example, when a user apparatus UE that is residing in a cell and that receives NS_05 from the base station eNB uses the number of RBs corresponding to NS_05 of FIG. 1, A-MPR equal to or less than 1 dB is permitted for a transmission power defined in “6.6.3.3.1 Minimum requirement (network signaled value “NS_05”)” of the non-patent document 2.
The NS value is defined as necessary for each band (operating band) and channel bandwidth (channel bandwidth). Although the NS value is broadcasted from the network, the value of A-MPR is implemented in the user apparatus UE. Thus, the network side only determines whether to apply it or not, and broadcasts the NS value.
Operation of a user apparatus UE receiving an NS value that is not defined for all channel bandwidths of a band that the user apparatus uses or for a specific channel bandwidth of the band is not specified. However, the user apparatus UE can understand NS_01 (no A-MPR) by default in any band and any channel bandwidth.